1. Field of the Invention
This invention relates generally to personal audio sets, and more particularly to a personal audio set with adjustable force mechanisms.
2. Description of the Related Art
Personal audio sets, commonly known as headphones, earphones, headsets, and the like, are gaining in popularity. The typical personal audio set includes a frame containing an earphone that is usually positioned over, on, or inside a wearer's ear. In cases where the audio set is a headset, a microphone is also typically positioned near the wearer's mouth.
Earphones for use with various kinds of audio sets for plugging into MP3 players, video game consoles, and different kinds of communication equipment have been in general use heretofore. Usually, a pair of earphones are attached to opposite ends of a bendable plastic or metal band that is worn over the head of the user such that the earphones are engaged with the ears of the user. These types of mounting structures are known as “over-the-head” mounts. Sets of this type have the disadvantage of being cumbersome to maintain in good aural connection with the wearer's ear and relatively uncomfortable to wear for extended periods of time.
For example, typical over-the-head mounts have earphones connected to a headband that is formed substantially into a C-shape with a predetermined curvature so that the width between both ends thereof is narrower than the average head width of the ordinary adult user. When the earphones are used, the user opens out the headband in the right and left direction and wears the earphone units by holding them to the wearer's ears. When the earphones are worn, the headband is curvedly deformed so that the radius of curvature thereof increases, by which a bent compression force (restoring force) is generated in the headband in the direction such that the initial radius of curvature is restored. In essence, the bent compression force is exerted in a direction such that the radius of curvature decreases.
This bent compression force of the headband is determined by the difference between the initial radius of curvature and the radius of curvature at the time when the headphones are worn. Moreover, the physical properties such as shape and material of the headband are considered. Therefore, the headband is designed so as to give a good sense of wearing to the user having the average head width. However, the width of the human head varies considerably. When a user with a narrower-than-average head uses the typical headphone, the bent compression force is weaker than the force encountered by a user with a normal sized head. Likewise, a user with a wider-than-average head will experience a bent compression force that is stronger than the force encountered by the user with the normal sized head.
Over-the-head headphones with adjustable lengths permit self adjustment of the headband in order to accommodate a wearer's head size and other parameters. Often times the expansion mechanism allows the length of the headband to accommodate heads of various sizes, but produces the side-effect of reducing the initial radius of the curvature of the headband, producing a tight radius of curvature. This reduced radius causes an increase in the bent compression force as the length of the C-shaped headband is increased. More specifically, as the headband is lengthened, the length-adjustment system creates excessive force on the scull and ears, especially, if the wearer's head is bigger than the average. As the headband is shortened to accommodate smaller sized heads, the pressure is lessened, causing poor aural connection with the wearer's ear. Although this type of length-adjustment provides a quick way of adjusting for the size of the wearer's head, there is no satisfactory way of specifically tuning the force or pressure applied to the wearer's head and/or ears. Without being able to perform such tuning, the audio set may become uncomfortable to use.
Another method for detachably securing a personal audio set to a wearer includes securing the personal audio set to a headband that encircles the rear portion of the wearer's head. These types of mounting structures are commonly known as “behind-the-head” mounts. Known behind-the-head mounts have several drawbacks. For example, many are not sizeably adjustable, causing the headband to rest on a potentially uncomfortable position on the back of the wearer's neck. Moreover, like the over-the-head mounts, the pressure or force applied by the audio set onto the earphone and the wearer's ear is also not adjustable, making the device uncomfortable to wear for long periods of time when the force is too tight, and causing poor aural connection with the wearer's ear when the force is too weak.
Headphones, such as that described in Furuya et al. (U.S. Pub. No. 2007/0165900), provide for the adjustment of the length of the headband (to accommodate different sized heads) and simultaneous maintenance of a constant pressure to the user's ear, regardless of the size or shape of the user's head. However, there is no way to adjust the pressure levels, for example, according to the user's preferences over time. After long time use, a user's ears may become more sensitive to the uniform pressure setting.
Other headphones include a headband with dual pivots, such as that described in Pelt et al. (U.S. Pat. No. 4,404,434), which enable the headphone to be folded-in for ease of transportation when not in use. The pivotal connection on these types of headphones only permit changing from a single operating position to a transport position. Thus, the pressure or force felt by a user in the operating position is not adjustable.